DENVER—The Colorado Court of Appeals has dismissed lawsuits against three companies tied to the deaths of five workers at a Colorado power plant in 2007.

In a ruling Thursday, the appeals court agreed with a judge that there was no evidence that the companies violated their duties or failed to provide adequate warnings of a fire hazard.

The workers died after a fire broke out inside a pipeline at Xcel Energy's Cabin Creek hydroelectric plant near Georgetown, about 40 miles west of Denver. The men were inside the pipeline resealing it at the time.

Families of the victims and four injured employees sued KTA-Tator Inc., Structural Integrity Associates Inc., and Graco, Inc., claiming the companies were negligent.